Put nuts, sugar, and salt in a food processor and pulse until ground. Pulse in the melted butter. Press the mixture evenly into the prepared pie plate. Make sure you even it out. Bake 12 to 15 minutes, or until browned and fairly set. It may still be a little soft when it comes out of the oven; don't worry, it will firm up. Coll completely before filling, especially if the filing is no-bake.